Dynamics of Macromolecules Grafted in Spherical Brushes under Good Solvent Conditions

Abstract

Spherical polymer brushes have a structure intermediate between star polymers and polymer brushes on flat substrates, and are important building blocks of polymer nanoparticles. Molecular dynamics simulations are presented for isolated spherical polymer brushes under good solvent conditions, varying the grafting density as well as the chain length, using a coarse-grained bead–spring model of flexible chains. We complement previous work on the static properties of the same model by analyzing the chain dynamics, studying the motions of monomers in relation to their position along the grafted chains, and extract suitable relaxation times. A qualitative discussion in terms of the Rouse model is given, as well as a comparison to corresponding work on planar brushes. We find that the end monomers relax faster than monomers further inside along the chain, as previously observed for planar brushes, but at variance with theoretical expectations. The relevance of our findings for experimental work is briefly discussed.